1. Field of the Invention
The invention relates to a light source device using optical fibers which is used for optical decoration and for illumination of the inside and outside of a room. The invention furthermore relates to an irradiation apparatus for photopolymerization which is used for dental treatment.
2. Description of Related Art
Conventionally, a light source device using optical fibers is known in which the light source is located in a position distant from the illumination position and in which the light from the light source is delivered by optical fibers to illuminate and decorate the inside and outside of a room.
There are different light sources for this light source device using optical fibers. However, inexpensive filament lamps are very common.
Recently, there has been a greater and greater demand for bright illumination of the inside and outside of a room by increasing the light intensity from optical fibers. Furthermore, there is a demand for effective decoration with brighter light in the optical decoration of the inside and outside of a room.
To meet this demand the following was done as the most simple means.
The input power of a filament lamp was increased, specifically the input power having been changed from 70 W to 100 W. In this way, the total light flux being emitted from the filament lamp itself is increased. The light intensity from the optical fibers was thus increased.
However, if the input power of the filament lamp is increased, accordingly the heat radiated from the filament lamp also increases. As a result, the defects arose that, in the course of operation, the color of the reflection surface of the reflector changes, the reflection factor gradually drops so that the light intensity from the optical fibers drops.
Furthermore, at an increased input power of the filament lamp, there were the following disadvantages:
The diameter or the length of the filament becomes greater. For this reason, the filament becomes far larger than a point source of light. Even if the filament is positioned at the first focal point of a reflector which is an ellipsoid of revolution, at the second focal point, the light is focused with scattering of a constant size because the filament has a certain size. Therefore, the light could not be focused with high efficiency onto the end face of the optical fiber positioned at the second focal point. In other words, there was the disadvantage that the light emitted by the filament lamp was not incident with high efficiency in the optical fibers.
To correct these problems, it can also be imagined that the cross sectional area of the end face of the optical fiber positioned at the second focal point be increased. However, increasing the cross sectional area only in this region is not ordinarily done, but generally optical fibers with a large cross section are used; this led to the defect of increased cost of the optical fibers. Furthermore, in optical decoration, there was also the disadvantage that, depending on the state of the arrangement of optical fibers, optical fibers with a large diameter cannot be used since they adversely affect the decorative effect.
The invention was devised to eliminate the above described defects in the prior art. Therefore, a primary object of the present invention is to devise a light source device using an optical fiber in which the light emitted from a filament lamp is incident on the end face of the optical fiber and emerges from the optical fiber with high efficiency. Here, xe2x80x9coptical fiberxe2x80x9d is defined as an individual fiber and also a group of fibers (fiber bundle).
In accordance with the invention, for a light source device using an optical fiber in which the light emitted from a filament lamp is focused and reflected by a reflector and is incident on the end face of the optical fiber, the object is achieved in that the reflector is an ellipsoid of revolution, that at the first focal point thereof there is a filament coil of the filament lamp and at a second focal point thereof the end face of the optical fiber is located, furthermore, that the condition is met that:
xcex1xe2x89xa620 (xcex1=Axc3x97(C/B))
where the area of the filament of the filament lamp is A (mm2), the area of the incidence face of the optical fiber is B (mm2), the value of the focal distance, i.e. the value of f2/f1, is C, the distance between the apex of the reflector and the first focal point is f1 and the distance between the apex of the reflector and the second focal point is f2.